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1 //
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24 // ********************************************************************
25 //
26 //
27 //
28 // Author: Maria Grazia Pia (Maria.Grazia.Pia@cern.ch)
29 // Sebastian Incerti (incerti@cenbg.in2p3.fr)
30 // Nicolas A. Karakatsanis (knicolas@mail.ntua.gr)
31 // History:
32 // -----------
33 // 31 Jul 2001 MGP Created
34 // 27 Jun 2008 SI Add check to avoid FPE errors
35 // 08 Dec 2008 NAK Log-Log interpolation math formula streamlined,
36 // self-test function
37 // 14 Jun 2008 NAK New implementation for log-log interpolation
38 // after directly loading
39 // logarithmic values from G4EMLOW dataset
40 // -------------------------------------------------------------------
41
42 #include "G4LogLogInterpolation.hh"
43
44 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
45 // Constructor
46 G4LogLogInterpolation::G4LogLogInterpolation()
47 { }
48
49 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
50 // Destructor
51 G4LogLogInterpolation::~G4LogLogInterpolation()
52 { }
53
54 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
55 G4VDataSetAlgorithm* G4LogLogInterpolation::Clone() const
56 { return new G4LogLogInterpolation; }
57
58 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
59 G4double G4LogLogInterpolation::Calculate(G4double x, G4int bin,
60 const G4DataVector& points,
61 const G4DataVector& data) const
62 {
63 G4int nBins = G4int(data.size() - 1);
64 G4double value = 0.;
65 if (x < points[0])
66 {
67 value = 0.;
68 }
69 else if (bin < nBins)
70 {
71 G4double e1 = points[bin];
72 G4double e2 = points[bin+1];
73 G4double d1 = data[bin];
74 G4double d2 = data[bin+1];
75 // Check of e1, e2, d1 and d2 values to avoid floating-point errors when estimating the
76 // interpolated value below
77 if ((d1 > 0.) && (d2 > 0.) && (e1 > 0.) && (e2 > 0.))
78 {
79
80 value = std::log10(d1)+(std::log10(d2/d1)/std::log10(e2/e1)*std::log10(x/e1));
81 value = std::pow(10.,value);
82 }
83 else value = 0.;
84 }
85 else
86 {
87 value = data[nBins];
88 }
89 return value;
90 }
91
92 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
93 // Nicolas A. Karakatsanis: New implementation of log-log interpolation after directly loading
94 // logarithmic values from G4EMLOW dataset
95 G4double G4LogLogInterpolation::Calculate(G4double x, G4int bin,
96 const G4DataVector& points,
97 const G4DataVector& data,
98 const G4DataVector& log_points,
99 const G4DataVector& log_data) const
100 {
101 G4int nBins = G4int(data.size() - 1);
102 G4double value = 0.;
103 G4double log_x = std::log10(x);
104 if (x < points[0])
105 {
106 value = 0.;
107 }
108 else if (bin < nBins)
109 {
110 G4double log_e1 = log_points[bin];
111 G4double log_e2 = log_points[bin+1];
112 G4double log_d1 = log_data[bin];
113 G4double log_d2 = log_data[bin+1];
114
115 // Values e1, e2, d1 and d2 are the log values of the corresponding
116 // original energy and data values. Simple linear interpolation performed
117 // on loagarithmic data should be equivalent to log-log interpolation
118 value = log_d1 + (log_d2 - log_d1)*(log_x - log_e1)/(log_e2 - log_e1);
119
120 // Delogarithmize to obtain interpolated value
121 value = std::pow(10.,value);
122 }
123 else
124 {
125 value = data[nBins];
126 }
127 return value;
128 }
129